1. Field of the Invention
The invention relates to an apparatus for applying a liquid coating to the edge portions of work pieces. More particularly, the invention relates to a belt mounted on and driven around pulleys mounted in a horizontal plane, the belt having a paint-applying surface configuration which conforms generally to that of the edge portion of a work piece to be coated. The apparatus is used to coat raw, beveled and tenoned edge portions of previously face coated, decorated panel materials such as fiberboard ceiling tiles and panels.
2. Description of the Prior Art
In the formation of decorative fibrous panel board and acoustical ceiling tiles in the past, a prime coat and an intermediate coat of paint were applied to one surface of the material in the course of its manufacture. The material was then cut into the desired length and width. The boards were then tenoned, and bevels formed thereon were ironed and coated with a prime coat of paint. The boards and bevels thereon then received a finishing coat of paint in a separate operation.
It has been recognized in the past that it would be desirable to eliminate the separate operation required for applying the finish coat and be able to obtain a finish-coated work piece directly from the tenoner. However, coating of the beveled edges formed in the tenoning operation has presented a problem in the past. Since fiberboard is porous, the cross-cut surfaces of the beveled portions have loose fibers, fiber ends, and voids which, when painted, have a rough texture and a color which contrasts with the coated face of the work piece. It has also been desirable, due to the dimensional instability of the product, to be able to not only coat the angled beveled edge portion of the work piece, but to also coat part of the remaining edge detail consisting of both a vertical and a horizontal surface since this would eliminate dark lines produced by exposed, unpainted board as the tiles grow and shrink while adjusting to humidity changes after installation. Former methods of coating the edge portions also resulted in portions of the edges being skipped and receiving little or no paint. This resulted because the bevels must be coated consistently and accurately at line speeds up to 200 feet per minute, and because the boards may shift slightly as they travel through the tenoner or the board may be warped slightly. Another problem involved in attempting to obtain a finish-coated product directly from the tenoner arises from the fact that, since the face of the board would necessarily be finished prior to the bevel coating, complete coverage of the bevel without any noticeable bevel paint on the face is required. Application of coatings of the desired thickness on the edge portions of the work pieces have also been a problem in the past.
Typical of the apparatus used in the past to coat beveled edges of panel boards are those disclosed in U.S. Pat. Nos. 2,165,210 and 2,811,133. In the case of U.S. Pat. No. 2,165,210, a rotatable disc having a circular plane face is inclined at an angle to the horizontal and dips into a supply of coating composition as it rotates, thus transferring a film of the coating composition to a beveled edge surface of a work piece. In U.S. Pat. No. 2,811,133, a similar arrangement is used for picking up the coating material and transferring it to another surface; however, in this case, the coating composition is transferred to a smooth transfer roll, which in turn transfers the coating to the beveled edge of the work piece.
U.S. Pat. No. 3,015,301 discloses an apparatus for painting grooves or bevels in the surface of a fiber wallboard unit and comprises a vertical paint transfer wheel having a beveled paint-carrying and applying peripheral face. A paint spray gun mounted adjacent thereto supplies a uniform coat of paint directly to the peripheral face of the transfer wheel for application to the grooved or beveled portion of the work piece.
U.S. Pat. No. 1,268,891 relates to an apparatus for applying a coating to ceramic tiles. The apparatus includes an endless belt which is mounted for travel around a pair of rollers and is provided on its outer surface with transverse grooves or channels. As the belt advances around the rollers, a portion of the belt is submerged in a tile glazing solution contained in a trough or reservoir. Thus, the grooves or channels are filled with the solution which is then carried upwardly over the top roller and applied to the surface of a tile being conveyed past the applicator.
U.S. Pat. No. 3,185,130 relates to a coating apparatus for applying a layer of liquid coating material of uniform thickness to the edge portion of a work piece. The apparatus includes a pick-up roller, the lower portion of which is immersed in a coating material. As the pick-up roller rotates, the coating material is carried into contact with an applicator roller which applies the material to an article being conveyed therepast. The applicator roller is continuously urged toward the article being coated by means of a coil compression spring, thereby assuring the desired contact pressure between the applicator roller and the article being coated.
None of the prior art disclosures provide a solution to the problems aforementioned.
The coating applicator apparatus of this invention provides a device which will enable finish-coated, beveled edge ceiling boards and panels to be obtained directly from the tenoning operation, thus eliminating a step in the production operation and resulting in a substantial savings of labor, material-handling time, and coating material.